Core slots have openings directed towards the center of a dynamo electric machine core, like the configuration of stators of DC Brushless motors. The wire coils consist of wire turns having portions positioned within the slots and across the end faces of the core. With such coil and core configurations, delivery of the wire from the needle occurs by causing repeated and sequential relative motions of translation, rotation and radial translation between the needle and the core.
Either the core or the needle can be moved to generate the relative motions. The relative translations are usually parallel to the center axis (O) of the core in order to form rectilinear portions of the wire coils, which are placed within the slots and beyond the ends of the core. The relative rotational motions are usually around the center of the core in order to form bridging portions between two wire coils that are placed across the end faces of the core. The relative radial translations are usually in the radial direction of the core in order to place the turns of the coil according to a predetermined positioning arrangement, usually referred to as “stratification”, along the radial extension of the slots. Winding principles of this kind are well known and described in U.S. Pat. Nos. 6,533,208, 6,991,194 and 6,622,955 now assigned to the assignee of the present application.
In winding scenarios for optimizing the stator dimensions and increasing the amount of wire that is required to fill the slots, the needle may not move within the slots of the core to deliver the wire. This is particularly due to the large dimensions of the needle with respect to the slot openings through which the needle would need to pass to enter or exit the slots. In addition, due to the large quantity of wire filling the slots, enough slot spacing would lack for any movement of the needle.
It follows that for these scenarios it is desirable that the needle is kept constantly outside the slots during winding. Accordingly, the wire leaving the needle needs to be deflected and guided for entering the slots to reach required predetermined positions to form the wire coil. Only in this manner can the turns of the wire coil be deposited regularly within the slots, i. e. with a desired position order and without crossing one another, to achieve a coil having a high amount of wire placed in a minimum slot space. The accuracy with which the wire is positioned to form the wire coils is influenced by the speed of relative motion of the needles with respect to the core, and by the positioning accuracy that occurs in the operations and devices for guiding and positioning the wire during winding.
U.S. Pat. No. 3,338,526 provides movable needles for winding stators with wire guides, which are positioned adjacent to the ends of the stator poles. The wire guides are sustained by support means located within the interior of the stator. Modern brushless cores like those wound according to the invention are designed to be extremely compact with high pole and wire occupancy. This means that the size of the cylindrical interior of the core leaves very little space for structural arrangements required to support or move the wire guides as shown in U.S. Pat. No. 3,338,526.
U.S. Pat. No. 2,573,976 also provides movable needles for winding stators with wire guides, which are positioned adjacent to the ends of the stator poles. The needle is constrained to move outside the slot of the stator during the translation strokes that bring the needle between the two ends of the stator. At the end of the stator, the needle moves in a radial direction to bring the wire over a winding guide and into the slots. The wire is then deflected by the wire guide onto further wire guides having a conical configuration. The further wire guides definitely direct the wire against the end of the stator according to a random disposition.